Anyone care to explain what happened that there are audio complaints and breakages? What part did they rewrite? I see this comment a lot, but googling doesn't find a quick answer.
For the most part, it's not a technical issue at all but a cultural one : pro audio users are notoriously, almost pathologically conservative when it comes to software upgrades.
You'll find plenty of threads on forums like Gearslutz, asking for tips on how to downgrade brand new Macs to an older version of macOS that doesn't even support their hardware. Or 2019 threads asking if it's now safe to upgrade to High Sierra. They're typically 2-3 versions behind. Why ? Older is just safer, better in their worldview.
In that context, audio developers know they have customers on their side against "evil Apple that's always breaking everything for no benefit", and every year in September/October they get away with emails that read like Apple just unexpectedly dropped a huge bomb on them out of the blue, and it'll take them 6-12 months to get ready, like WWDC and 3-4 months of developer betas never happened.
While this take is accurate, it's because they want to _do audio stuff_ and not debug computers.
As a DJ, My Serato set up _works_. I don't have any show stopping bugs, and I don't want any new features. It's running on Sierra with an older version of Serato from like 2 years ago. Why do I need to upgrade the OS?
When I'm playing in the Club, I shut off wifi/bluetooth, and everything else that I can.
If I could simplify even more, I would. General Purpose computers are both great and a liability when it comes to digital audio especially for any live performance.
You're right, users absolutely should not have to debug computers and live performance is especially sensitive to realtime constraints.
It's the developers job to do so, and they're basically procrastinating for as long as they can, not heeding Apple's deprecation warnings for _years_ and then trying to blame them in front of users when st finally hits the fan, pretending they couldn't possibly have known. That's simply dishonest.
I thought professional audio developers try to exploit very low level access to the hardware for the sake of minimizing latency. If these same exploits allow system vulnerabilities, it seems to make sense that developers of macOS are constantly changing the software in ways that unintentionally impact anyone writing kernel extensions or other software that tries to access the hardware at a low level.
Most of the developers emailing their users in panic are not in this situation though.
They're writing audio plugins using the AU or VST APIs. They don't ever touch hardware or even deal with realtime constraints directly : they just fill buffers as far as they can and pass them on to the host DAW application, which together with audio interface drivers + the OS deal with the hard stuff.
In this case, it's not conservative me not wanting to upgrade (this computer is actually only a month old). It's vendors saying they can't guarantee that their software will work. Several of them.
This is the first version of macOS that doesn't support 32-bit applications. Most of the software in question hasn't been updated in years so people are hesitant to upgrade. It's mostly a legacy issue.
On top of using their main application (DAW), which is most likely 64-bit, musicians tend to use a ton of plug-ins; some commercial, some freeware. Many if not most are 32-bit only and probably will never be updated (abandonware, or just old unsupported releases from commercial vendors).
Basically for many musicians, upgrading macOS will mean killing some of their plugins.
